Monson has been on the Stamps' coaching staff for nine years including five seasons as linebackers coach. He was on staff for Calgary's Grey Cup victories in 2014 and 2018.
"Brent has been a valuable member of our coaching staff for a long time and I'm very confident that he will do an excellent job in the defensive coordinator's role," said Stampeders head coach Dave Dickenson. "Brent is a hard worker who knows our personnel very well. Just as importantly, the players know him and will play hard for him."
"I'm very thankful to Dave Dickenson and to John Hufnagel for the confidence they've shown in me by giving me this opportunity," said Monson. "This organization has become like a family to me and I'm excited for the chance to continue working with this great defence. I'm looking forward to this new challenge and will work extremely hard to make sure our team continues to be successful."
In 2018, Monson helped oversee a defence that allowed a league-low 17.2 points per game to opposition offences. The Calgary defence also allowed the fewest touchdowns (27) and the fewest rushing yards (86.5 per game) while sharing the league lead in turnovers forced (49) and sacks (45).
In addition to working with a linebacker group that included standout Jameer Thurman on the weak side and CFL all-star Alex Singleton in the middle, Monson was the acting defensive coordinator for an Aug. 25 game against the Winnipeg Blue Bombers while DeVone Claybrooks was in hospital due to illness.
The Stamps have allowed the fewest offensive points in the CFL in all four years of Monson's second stint as Calgary's linebackers coach. He was previously linebackers coach in 2010 and defensive line coach in 2011 before acting as running backs coach from 2012-14. He also served as the team's strength and conditioning coach from 2010-14.
The 33-year-old Hamilton, Ont., native is an alumnus of McMaster University. He joined the Stampeders in 2009 as a member of the team's video department before being added to the coaching staff in 2010.